The absence of palliation and curative therapy for various end-state chronic pulmonary diseases emphasizes the therapeutic potential of clinical lung transplantation. Success in this venture requires standardization, in an experimental animal model, of techniques such as determination of histocompatibility, detection of early rejection, use of immunosuppressant therapy, plus the characterization of lung allograft rejection. Because of similarities of the lower primates to the human, the baboon would represent a unique model for these studies. The objectives of the proposed research are: 1. To determine the effect of goal antibody to baboon thymocytes (ATG) upon the recipient's immunologic response pre- and post-operatively. 2. To evaluate the effect of ATG alone on the survival of lung allografts and in common with other immunosuppressives. 3. To evaluate the functional capacity of the primate lung allograft and factors influencing impaired function. 4. To delineate the characteristics of various rejection stages of primate lung allograft rejection by light microscopic, immunofluorescent, and ultrastructural studies. 5. To evaluate mixed lymphocytes culture and tissue typing in matching baboon donor and recipient in lung allotransplantation. 6. To detect early lung rejection using leukocyte migration inhibition, reactive lymphocyte blastogenesis and Cr51 cytotoxic assays. 7. To evaluate lung allograft recipients that are initially treated with ATG followed by donor bone marrow cells.